This invention relates to press apparatus and tooling therefore used to convert the shells for self opening cans and the like. Such presses have been known for many years, and typically come in a range of sizes which are designated by tonnage, specifying the predetermined pressure that the press is designed to produce in consecutive pressing operations. However, a press of a given tonnage may in fact exceed its design limits for short periods of time during its operation. Also, the tooling for the press may be so designed that while momentary pressures exceed the designed tonnage, the pressure peaks are the result of the interaction of tooling in a minor part of the available bed-ram area of the press. However, continued such overloading may result in severe and/or premature wear, and to prevent such wear it is advisable to operate within design limits, and to seek optimum production through other means.
A sequence of preparing can ends, complete with scoring and attached tab for opening the end, is described in Fraze U.S. Pat. No. 3,366,086 issued Jan. 30, 1968. This patent discloses the typical steps for creating the can end, creating the tab, making the integral rivet connection between the tab and the end, and passing the completed end to an apparatus where the can body is filed and the end is attached.
U.S. Pat. Nos. 3,470,837 issued Oct. 7, 1969 and 3,550,546 issued Dec. 29, 1970 illustrate tooling and related apparatus for high production manufacturing of can ends in a typical single action press, where one completed end is discharged from the press for each complete press cycle. Typical of such designs, intermittently rotating carriers are provided, indexed step wise in coordination with the press cycle, to perform the sequence of operations in making the completed can end. Many such apparatus are in commercial use, and a typical press for that purpose is the Minster P-2 45 press, manufactured by Minster Machine Company, Minster, Ohio, U.S.A. Thus presses of this type are currently available on the used machinery market, thus the opportunity exists to modernize such existing single acting presses which, subject to replacement of bearings, drives, etc. are capable of many additional years of use.
More recently, there have been commercial installations of larger conversion presses wherein a two-lane conveyor belt extends front to back of the press, through in-line conversion tooling. Cooperating with the conveyor are up-stacker and down-stacker mechanisms located in front of and rearward of the slide, to carry a double lane of shells through the tooling in this press. The shells are received in circular apertures in the stainless steel conveyor belt, which is moved stepwise through the press in synchronism with the opening and closing of the tooling. To one side of this conveyor mechanism there is conventional in-line progressive tab tooling to form tabs from a metal strip which enters the press from one side.
Such presses provide two-out capacity, but the tooling is arranged in such fashion that the entire set of tab tooling is to one side of the center of the press, and a substantial off-center or asymmetric loading exists on the slide.
The present invention, therefore, deals with the provision of modern balanced tooling for the production of can ends with a high degree of efficiency, and also to a design with such balanced style of tooling heretofor not achieved. Can end manufacturers are thus able to renovate existing capital equipment, or to purchase new or renovated equipment having the improved manufacturing techniques.